Author Topic: Zeiss 940 Scanning electron microscope  (Read 8940 times)

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Offline eV1Te

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Re: Zeiss 940 Scanning electron microscope
« Reply #25 on: November 24, 2013, 07:54:22 am »
Very interesting to see other people with SEMs at home. I have a Jeol JSM-T200 in my living room at the moment. I made a video some time back, just showing a light bulb filament while recording the screen.

Would anyone we interested in a teardown before I have to get rid of it?



Some comments on your problems:
-Helium is your best bet (only option) to find leaks.
-Don't use to much of that special high-vacuum grease, even the best vacuum-greases evaporates in high vacuum. You should spread it almost as thin as one atomic layer, preferably no grease at all if not required to stop leaks. (but in order to just reach below 1 mbar, to start the turbo pump, you could probably seal the chamber with Vaseline)
-I have a few boxes of filaments to my SEM, do you have spare ones?
 

Offline SeanB

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Re: Zeiss 940 Scanning electron microscope
« Reply #26 on: November 24, 2013, 03:27:43 pm »
Very interesting to see other people with SEMs at home. I have a Jeol JSM-T200 in my living room at the moment. I made a video some time back, just showing a light bulb filament while recording the screen.

Would anyone we interested in a teardown before I have to get rid of it?



Some comments on your problems:
-Helium is your best bet (only option) to find leaks.
-Don't use to much of that special high-vacuum grease, even the best vacuum-greases evaporates in high vacuum. You should spread it almost as thin as one atomic layer, preferably no grease at all if not required to stop leaks. (but in order to just reach below 1 mbar, to start the turbo pump, you could probably seal the chamber with Vaseline)
-I have a few boxes of filaments to my SEM, do you have spare ones?

Teardown of course, and hopefully somebody wants it intact.
 

Offline samofab

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Re: Zeiss 940 Scanning electron microscope
« Reply #27 on: November 28, 2013, 12:07:51 am »
Quote
I have a Jeol JSM-T200 in my living room at the moment.

Thumbs up!

Quote
-I have a few boxes of filaments to my SEM, do you have spare ones?

I have only the one that I found inside. Everybody is saying that rebuilding the filaments in cheap and easy, but living in Europe it ads up to a significant amount. Do you have a picture of the filemant with approx. dimensions?

Quote
but in order to just reach below 1 mbar, to start the turbo pump, you could probably seal the chamber with Vaseline

Well, after I got new seals for my aperture I still get the huge leak on the same location. I suspect that I'll have to disassemble the whole column.. running out of options here.

Disassembled aperture holder image for your pleasure is in attachment.

On a different note: I'm thinking of at least partially giving up on the electronics unit. I'm thinking of just building a ramp raster generator from the two DACs in STM32, plug it into existing working power amplifiers and oscilloscope and hopefully I'll get an image.

In an effort to do that I decided to test the photo-multiplier supply and it doesn't work.. or to be precise: board contains two completely populated 1.5kV power supplies and the one that was wired to the photo-multiplier is dead, but the completely unused one is fine (yes, there is actually a second supply that with certainty wasn't used for anything).

Quote
Back up all of those Eproms before you go much further.

It's an excellent idea, but I don't have eeprom reader.. I could hack something together, but with current plan to forget about the Z80 parts, I don't think it's worth the effort.
 

Offline eV1Te

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Re: Zeiss 940 Scanning electron microscope
« Reply #28 on: November 28, 2013, 04:27:21 am »
Quote
I have a Jeol JSM-T200 in my living room at the moment.
Thumbs up!
Thanks!
Quote
-I have a few boxes of filaments to my SEM, do you have spare ones?
I have only the one that I found inside. Everybody is saying that rebuilding the filaments in cheap and easy, but living in Europe it ads up to a significant amount. Do you have a picture of the filemant with approx. dimensions?
These are filaments for my and most of Jeols tungsten filament microscopes (K-type filaments):
http://www.tedpella.com/apertures-and-filaments_html/tungsten-filaments.htm#anchor1407
Quote
but in order to just reach below 1 mbar, to start the turbo pump, you could probably seal the chamber with Vaseline
Well, after I got new seals for my aperture I still get the huge leak on the same location. I suspect that I'll have to disassemble the whole column.. running out of options here.

Disassembled aperture holder image for your pleasure is in attachment.

On a different note: I'm thinking of at least partially giving up on the electronics unit. I'm thinking of just building a ramp raster generator from the two DACs in STM32, plug it into existing working power amplifiers and oscilloscope and hopefully I'll get an image.

In an effort to do that I decided to test the photo-multiplier supply and it doesn't work.. or to be precise: board contains two completely populated 1.5kV power supplies and the one that was wired to the photo-multiplier is dead, but the completely unused one is fine (yes, there is actually a second supply that with certainty wasn't used for anything).

Before you disassemble to much (more old seals that can break, or misalignment of beam), just remove the aperture assembly completely and seal the hole with with some plastic or rubber if possible. I usually use just a flat piece of rubber in these cases that can cover the entire hole, which will be held in place by the vacuum.

I have been thinking about modifying the electronics for my SEM to, just a ramp generator for X and Y, and then measuring/controlling the position of these with a computer, which also analyses the signal from the photo multiplier (hence a digital SEM)

I will have to get rid of my SEM in the beginning of next year. I have no idea what to do with it! So if anyone wants parts from it, you are welcome to just pay the shipping. (unless I find someone who wants the entire thing, preferably in Sweden since shipping would be expensive!)
 


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